That which has witnessed one's youth, maturity and old age, itself remaining unchanged amid these changes, is the formless witness

All these experiences as father, wife, son, friend and  enemy were one and the same Mind appearing differently. All these distinctions disappear in the ultimate truth.

In the dream the mountain which is apparently insentient and material, is nevertheless still the  mind alone. Whether living or dead, conscious or unconscious thought or matter, all things are appearances of one and the same Mind. All these distinctions are seen by a Gnani as only the consciousness.

Ignorance: When one  knows that there is no duality, ignorance goes. And when one does not know what an illusion  is, there is ignorance. And when one  imagines time space and cause, there is illusion. Sunyavadin Buddhists who say everything is non-existence,:- then how does one see, hear, think?  All these differences, all this multiplicity, all this ignorance which regards the multiplicity as real, is caused by one's  own thinking.

That which has witnessed one's  youth, maturity and old age, itself remaining unchanged amid these changes, is the formless witness (soul or consciousness). 

The dream entity and the dream world are created out of consciousness and they are not different from it; similarly the waking world entity and waking world are also created out of consciousness.   When one knows that everything is consciousness then there is no need for yogic control of mind. Control presupposes second, a duality. Hence yoga is in the sphere of duality and is unnecessary to one who knows non-duality

Non dual wisdom requires investigate into the mind, analyzing the mind, which is in the form of the universe and the universe appears as waking or dream.  One has to the fact that, the mind rises and subsides from formless source, which is soul or consciousness. The consciousness is the innermost self. Therefore, one has to learn to judge the truth from the standpoint of the source from where the mind rises and subsides, not from the standpoint of the waking entity, which is the false self within the false experience.

As one gets convinced, certain, of the truth that the world is nothing but consciousness, and there is no second thing, then he gets a conviction that, all the three states to be consciousness in the midst of duality. Realizing the non-dualistic or Advaitic truth in the midst of duality is wisdom.